We have only had vaccines for roughly 200 years now. What about before then?

Viral pandemics have killed lots of people throughout history, but humans are still here. If the theory of decreasing destructiveness is all wrong, have we just been lucky so far?

Or is there another way forward?

“Some evidence suggests that SARS-CoV-2 will become part of the human respiratory virome, as had occurred with other coronaviruses, and coevolve with its host.”

https://pubmed.ncbi.nlm.nih.gov/35019068/

Btw, I don’t claim to KNOW anything technical about this. I just have questions.